Don't forget film prductions will also have specialist hair stylists etc, whose job it is to know how to get certain effects. Plus make up will often be applied to give skin a smoother appearance, just the same as on actor's faces.

And if that always fails, there's still CGI.

By all means try different things to get as smooth as you can, but seeing something, anything, in the movies and thinking it is an attainable goal isn't always realistic, for the simple reason that the the movies themselves aren't realistic.